1. Field of the Invention
The present invention relates to optical fiber ribbons for optical fiber telecommunication cables and a process of making the optical fiber ribbons. More particularly, the present invention relates to optical fiber ribbons that are color coded to visibly distinguish ribbons and to enable easy identification of the fiber #1 position.
2. Description of the Related Art
Optical fiber cable manufacturers frequently employ optical fiber ribbons, or multi-ribbons, in optical fiber cables to provide an organized structure that increases packing efficiency, facilitates rapid splicing, and simplifies fiber connections. Ribbon assemblies also provide a modular design that simplifies the construction, installation, and maintenance of optical glass fibers by eliminating the need to handle individual optical glass fibers.
Optical fiber ribbons generally include a plurality of optical fibers arranged in a planar array. Each optical fiber generally includes a core, a cladding, and primary and secondary coatings formed from an ultraviolet (UV) light curable material. The optical fibers are usually coated with an outer color layer applied to the secondary coating, i.e., an ink coating to distinguish the fibers from one another. In the alternative, a colorant may be added to the secondary coating to distinguish the fibers from one another.
Ink coatings facilitate identification of a particular optical fiber within a ribbon and allow one or more of the optical fibers to be selected for purposes of splicing, or the like. An ink coating typically increases the diameter of each optical fiber by 5-10 xcexcm, resulting in a 25-50 xcexcm wider ribbon (12-fiber ribbons) and a 10-20 xcexcm thicker ribbon.
Currently, the industry standard calls for using a clear ribbon matrix material to bind all the ink coated optical fibers therein. Each clear ribbon coating has an identifier printed thereon for distinguishing individual ribbons from the plurality of ribbons in a given fiber optic cable. However, the clear ribbons having print identifiers thereon are difficult to read in dark enclosures where fiber optic cables are typically deployed.
U.S. Pat. No. 6,122,428 discloses a ribbon assembly containing a plurality of coated optical fibers that are bound together by a matrix material. Each of the optical fibers has an ink coating for identifying the individual fibers. Additionally, in order to keep the ink coating on the individual fibers, the level of adhesion between the ink coating and the matrix material is adjusted to be less than the level of adhesion between the ink coating and the secondary coating of the optical fiber.
FIG. 1 illustrates an example of a conventional optical fiber ribbon 10 having a clear ribbon matrix coating 20 covering twelve optical fibers that are arranged in a parallel planar array. Each of the optical fibers 30 is coated with a primary coating (not shown) and a secondary coating 32. A color ink layer 34 overcoats the secondary coating 32 thereby adding 5-10 microns onto the optical fiber diameter. As a result, the fibers and the coating layers result in a overall diameter of approximately 250 microns.
The colored ribbon coating also suffers from the problem that unless the coating opaqueness is minimized to show the colors of the underlying optical fibers, then the colored ribbon coating still requires some level of printing thereon to identify the fiber #1 position.
It is an object of the present invention to provide a method of producing visibly distinguishable colored optical fiber ribbons and optical fibers.
It is a further object of the present invention to provide a peelable optical fiber ribbon that removes an ink coating from optical fibers while maintaining color distinguishable optical fibers.
These objects are accomplished, at least in part, by covering an optical fiber with a colored secondary coating and applying an ink coating onto the secondary coating. A plurality of optical fibers are arranged in a planar parallel array and enveloped with a clear ribbon matrix coating to bond the optical fibers together in the planar parallel array. In the preferred embodiment, the clear ribbon matrix coating is applied over the ink coating when the ink coating is not fully cured so as to produce a stronger bond between the ink coating and the clear ribbon coating than between the ink coating and the secondary coating.
Alternatively, this property may be achieved by chemistry formulation differences between the coatings that allow the ink coating to prefer crosslinking with the ribbon coating rather than the fiber""s secondary coating. Any combination of level of cure, chemistry formulation differences, or any other method of achieving the desired adhesion relationship described are within the scope of the present invention.
An example of a ribbon produced in accordance with the present invention would be as follows: if fiber #1, which has a blue secondary coating, is further coated with black ink, and fibers #2 through #12 (for a 12 fiber ribbon) all have the appropriate colored secondary coating (see Table 1) and are further coated with white ink, then the finished ribbon will appear white with a black stripe along the side of the ribbon where the fiber #1 position is located.
The method of using the appearance of a stripe to locate a wire, pin, or fiber position is a commonly accepted industry standard in the copper wire ribbon industry and is equally applicable for optical fiber ribbons. Any color or colors may be used for either the stripe or the xe2x80x9cbulkxe2x80x9d colorxe2x80x94black and white are merely used as example. An additional stripe of the same, or different color than the fiber #1 stripe may be added by varying the color of other fibers across the cross section of the ribbon. This technique can be used to place an identifier stripe or stripes on a ribbon to differentiate between two ribbons of the same base color contained in the same cable (i.e., the white ribbon and the white ribbon with stripe).
Ribbons produced in this manner require absolutely no printing because the colored ink provides all the necessary identifiers. Any ribbon may be specifically identified by the apparent color created by the ink coating applied to fibers #2 through #12, and the fiber #1 position in any selected ribbon may be easily identified by the apparent stripe created by the ink coating applied to fiber #1.
Additionally, a specific optical fiber may thus be located by, first, selecting a desired optical fiber ribbon based on the colored ink markings therein, and, second, peeling away the ribbon coating which removes the ink coating to expose the optical fibers which are uniquely identified by the color of their secondary coating.
It is a further object of the present invention to provide an optical fiber ribbon including a plurality of optical fibers therein, wherein each optical fiber has a different colored secondary coating that is covered by an ink coating, and wherein the ink coating is a same color over a majority of the plurality of colored optical fibers.
Other objects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description read in conjunction with the attached drawings and claims appended hereto.